The properties of neurons in the nucleus ventralis lateralis (VL) of thalamus were examined by anatomical and lectrophysiological methods and the following results were obtained: 1) There were two types of projection fibers from VL to the motor cortex. One type projected to a limited area of the cortex, the other arborized extensively and projected to a wide area of the cortex. 2) The widely arborizing projection fibers, i.e., wide projection fibers, showed a special terminal bush which was different from that of the specific projection fibers of VPL and spread as widely as 1.0 mm2 within the III layer of the motor cortex. 3) Neither narrow nor wide projection fibers carried specific information from the periphery but rather diffuse information arising from deep structures such as joints and periosts. 4) Both types of projection fibers branched somewhere in the white substance and projected to different areas of the motor cortex. 5) From these results, it is suggested that activities of single VL neurons can influence the activities of a group of cortical efferent zones which in turn produce simultaneous contraction of a group of muscles.